1. Field of the Invention
The present invention relates to a mounting arrangement for a diaphragm actuator used in a switching mechanism of a transfer unit in a four wheel drive automobile.
2. Description of Related Art
It is known to provide a transfer unit in a four wheel drive automobile to selectively transfer the drive power to the wheels from a two wheel drive state to a four wheel drive state, and vice versa. To effect the transfer, it is known to provide a vacuum-operated actuator (for example, c.f., Japanese Unexamined Utility Model Publication No. 59-76422). In one type of mounting arrangement, the actuator can be located separately from the transfer case, and an interconnecting means such as a rod extends between the transfer case and the actuator body in an exposed manner. It is necessary, in this arrangement, to provide a seal for both the transfer case and the actuator body and to electroplate the exposed rod or the like to prevent corrosion, resulting in additional cost. Another arrangement is to attach the actuator to the transfer case. An example of such an arrangement is shown in FIG. 3 of the attached drawings, in which a body of an actuator 2 is attached to planar adjoining surfaces 1d and 2d of a transfer case 1. With this type of arrangement, it is necessary to provide the planar adjoining surfaces 1d and 2d over a relatively wide region to ensure a reliable attachment of the actuator, which in turn requires a machining operation over a relatively wide planar surface. In addition, in this type of arrangement, the mounting angle of the actuator relative to the transfer case is not easily adjustable, and an interchange of the components is difficult.